(i) Field of the Invention
This invention relates to an abrasion, wear and impact resistant hard facing coating and, more particularly, relates to an abrasion, wear and impact resistant coating, and its method of production, on equipment components used in high wear applications typified by the mining of oil sands.
Mining of oil sands involves excavation and transfer of huge volumes of stratified sand saturated with bitumen for recovery of hydrocarbons. The sand essentially is a quartz sand angular in shape and as a result very abrasive to steel equipment. The hard facing of steel equipment to resist wear and erosion by coating exposed steel surfaces with tungsten carbide particles dispersed in a matrix of mild steel or a nickel- or cobalt-base alloy is known. U.S. Pat. No. 4,013,453 for example discloses hard surfacing of a metal substrate by coating with a nickel-base matrix powder mixed with coarse tungsten carbide particles to resist wear and abrasion. It is stated that such coatings are sensitive to thermal cracking and spalling due to the brittle nature of the coating.
The hard facing of equipment used for the mining and handling of oil sands is particularly sensitive to wear, to erosion due to abrasion, and to spalling due to the shock of impact from dropping of large lumps of oil sand on shaker boxers or rotary breaker drums for screening the sands.